三角帆蚌hcSRCR1基因的克隆及在不同壳色选育系中的表达模式

清道夫受体(SR)是一类对化学修饰的脂蛋白具有很强结合活性的糖蛋白家族。本研究通过RACE方法克隆得到三角帆蚌hcSRCR1基因cDNA序列,该序列全长1 000 bp,其中开放阅读框819 bp,编码272个氨基酸,预测分子量为28.16 ku,理论等电点为5.55;预测含有2个SRCR结构域和6个保守的半胱氨酸残基。qRT-PCR和Western blot结果显示,hcSRCR1 mRNA和蛋白表达模式基本相同,均在三角帆蚌外套膜中表达量最高,在其他组织中的表达量普遍较低,且在紫色选育系外套膜组织中的表达量显著高于白色选育系。外套膜原位杂交结果显示,hcSRCR1基因主要在外套膜外褶的内、外上皮细胞层以及腹膜处的上皮细胞层中表达。研究表明,三角帆蚌hcSRCR1基因与贝壳珍珠质颜色形成具有一定相关性,可为进一步研究该基因在珍珠颜色形成过程中的调控机理提供基础资料。

Cloning and tissue expression of a novel hcSRCR1 gene in differential inner-shell color pearl mussel Hyriopsis cumingii

As a superfamily of glycoproteins, scavenger receptors play a crucial role in the identification and assembly of chemically modified lipoproteins. In this study, cDNA of Hyriopsis cumingii scavenger receptor cysteine-rich gene (hcSRCR1) was cloned by using rapid amplification of cDNA ends (RACE) approaches, then the bioinformatics and expression profiles were analyzed. The complete hcSRCR1 cDNA consists of 1 000 nucleotides with a 819 bp open reading frame encoding 272 amino acid residues. The molecular weight of hcSRCR1 was 28.16 ku and pI was 5.55. It was also predicted that protein hcSRCR1 had two scavenger receptor cysteine rich domains and six conserved cysteine residues. qRT-PCR and Western blot showed that hcSRCR1 was constitutively expressed in a wide range of tissues with the highest expression level in the mantle. Moreover, differential expression analysis revealed that hcSRCR1 was more highly expressed in the mantle of purple line mussels compared to white line mussels. In situ hybridization investigations of the precise expression site of hcSRCR1 mRNA in the mantle showed that hcSRCR1 mRNA is specifically expressed in the inner epithelial cells of the outer fold mantle, as well as throughout the outer epithelium of the outer fold and ventral mantle. Our results suggest that hcSRCR1 play a role in the formation of shell and pearl color formation, and may provide useful information for further studies on regulation mechanism in the color formation of pearls.